This proposal is directed to the study of the possible role of salsolinol, an aberrant metabolite of dopamine, in the control of discriminative responding by ethanol. The ability of ethanol to serve as a discriminative stimlus in rats is well established and there is evidence that ethanol may produce similar effects in humans. Rats will be trained to discriminate 200 mg/kg ethanol from saline and, lower and higher doses will be tested to establish a dose-responsive relationship. Trained rats will, then, be tested with the dopamine-acetaldehyde products 3-carboxysalsolinol, (plus) salsolinol and (minus) salsolinol to investigate their ability to discriminate these simple alkaloids as ethanol. The dose-effect curves for ethanol discrimination will be compared to similar curves generated by testing a range of doses of 3-carboxysalsolinol to evidence a possible common site and/or mechanism of action for discriminability. The narcotic antagonist naloxone will be administered prior to both the training dose and ED50 of ethanol to evidence the possibility of opiate involvement in the discriminative properties of ethanol.